This invention relates to stable aqueous latexes of interpolymers containing vinylidene chloride and aliphatic conjugated dienes and to the use of such latexes as binders or adhesives in various applications such as in paper coating compositions, in carpet backsizing, in nonwoven fabrics, etc.
Aqueous colloidal dispersions of polymer particles, which are commonly referred to in the art as latexes are generally known to be useful, both alone and in various formulations, in a multitude of applications such as coatings, adhesives, impregnants, etc. In addition, a wide variety of such dispersions of differing homopolymeric and copolymeric composition (such as vinylidene chloride copolymers, styrene-butadiene copolymers, homopolymers and copolymers of acrylate and methacrylate esters, etc.) are known to have certain specific chemical and/or mechanical properties which render them especially desirable for particular end use applications. For example, aqueous polymer latexes comprising substantial or predominant amounts of vinylidene chloride copolymerized with generally relatively smaller amounts of other monomers are known to possess a community of desirable properties making them well adapted for wide variety of end uses. Among such properties are reduced flammability, low permeability to oxygen and water vapor, chemical inertness including resistance to greases and oils, good binding power for pigments, fillers, etc., high impact and tensile strength, and the like. See, for example, U.S. Pat. Nos. 3,254,044; 3,282,867; 3,291,768; 3,309,330; 3,310,514; 3,379,665; 3,472,808 and 4,002,801.
Unfortunately, however, the foregoing advantageous properties of the known vinylidene chloride latexes are accompanied, to greater or lesser degrees, by certain disadvantageous properties including limited flexibility and elongation, colloidal instability (e.g., sensitivity to, or coagulation upon, storage and/or exposure to mechanical shear), chemical instability (e.g., degradation and/or discoloration by exposure to polyvalent metal ions), water sensitivity, and, especially, heat and light instability (e.g., degradation and/or discoloration upon exposure to heat and/or light).
In view of the indicated disadvantages of prior art vinylidene chloride copolymer latexes, it is highly desirable to provide improved latexes of vinylidene chloride-containing polymers which overcome most or all of such disadvantages, particularly those related to chemical instability and to heat and light instability.